Chondrichthyes

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Dark ghost shark (Hydrolagus novaezealandiae) and the pale ghost shark (Hydrolagus bemisi), both are shortnose chimaera of the family Chimaeridae, found on the continental shelf around the South Island of New Zealand in depths from 30 to 850 m.

Both ghost shark species are taken almost exclusively as a bycatch of other target trawl fisheries

Golden Cownose Ray (Rhinoptera steindachneri)

Also known as the Pacific Cownose Ray, the golden cownose ray is a species of eagle ray (Myliobatidae) which occurs in the eastern Pacific, ranging from central Baja California south to Peru and the Galapagos Islands. Golden cownose rays like other eagle rays are a transient and highly mobile species, often forming large schools or moving in loose aggregations. R. steindarchneri feeds mainly on molluscs and other hard bodied invertebrates, using its plate-like teeth which are specialized for crushing and grinding. 

Classification

Animalia-Chordata-Chondrichthyes-Elasmobranchii-Myliobatiformes-Myliobatidae-Rhinoptera-R. steindachneri

Image: Atomische

February on this blog is going to be Daily Paleo Art Month! Because doing dinosaurs all last July was so much fun I want to do this thing again.
 Every weekday for the rest of the month I’ll be posting a new image of something strange, obscure, or just plain interesting from the fossil record – only this time we’re staying firmly outside of the Avemetatarsalia (pterosaurs and dinosaurs/birds) to give some less famous critters the spotlight.

#1: Helicoprion

A cartilaginous fish from off the southwest coast of the ancient supercontinent Gondwana (and later Pangaea), Helicoprion first appeared in the late Carboniferous (310 million years ago) and survived up until just past the massive Permian-Triassic extinction (250mya). Despite looking rather shark-like and possibly reaching sizes of around 6m (20ft) long, it was actually closer related to the chimaeras.

For a long time, the only parts of this animal known were bizarre buzzsaw-like spiral whorls of teeth, since cartilage skeletons very rarely fossilize. The ideas for just where in the body this structure was positioned were ridiculously varied.

The most recent reconstruction is based on CT scans of a well-preserved fossil with jaw and skull elements, which showed the whorl taking up the whole lower jaw. It also turns out Helicoprion had no upper teeth at all. It’s thought to have used this arrangement to shred and crush up squid and other soft-bodied marine prey, but there’s still very little known about how such a unique type of teeth evolved in the first place.

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The Narrownose chimaera (Harriotta raleighana), occurs in deep waters of the continental slopes in depths of 380 to 2,600 m in both the Atlantic and Pacific Oceans.  They are oviparous but nothing is known of spawning and reproduction and very few juveniles have been collected. It was filmed swimming 10 m above the seafloor in Hydrographer Canyon, off the coast of Nantucket Island in the US.

Just before a shark breaks the surface tension of the water

I came across this photo while perusing the good ol’ internet a few weeks ago, and now that I’m back from a mildly extended absence, I still want to share it. This image is stunning, to say the least. In my opinion, it shows off just how beautiful and mysterious these creatures are. It’s these minute glimpses into their environment and lives that captivates and motivates me to continue my studies.

Japanese Sawshark (Pristiophorus japonicus)

…a species of sawshark (Pristiophoridae) which occurs in the northwest Pacific Ocean around Japan, Korea, and northern China, where it inhabits the sandy or muddy bottoms of the continental shelves (at depths of 50-800 m). Japanese sawsharks are primarily “benthic” and will feed on a wide range of small bottom dwelling invertebrates and fish. 

Classification

Animalia-Chordata-Chondrichthyes-Elasmobranchii-Pristiophoriformes-Pristiophoridae-Pristiophorus-P. japonicus

Image: Opencago.info

eartharchives.org
Study shows sharks have personalities
For the first time a study led by researchers at Macquarie University has observed the presence of individual personality differences in Port Jackson sharks.

“Understanding how personality influences variation in shark behaviour – such as prey choice, habitat use and activity levels – is critical to better managing these top predators that play important ecological roles in marine ecosystems.”

Grey Bamboo Shark (Chiloscyllium griseum)

…a species of longtail carpet shark (Hemiscylliidae) which is occurs in the Indo-West Pacific Oceans, from the Arabian Sea to Pakistan, India, Malaysia, Thailand, Indonesia, China, Japan, the Philippines, and Papua New Guinea. Like other members of Hemiscylliidae, C. griseum typically occupies sandy and muddy bottoms of coastal waters and feeds on a range of small bottom dwelling invertebrates. 

Classification

Animalia-Chordata-Chondrichthyes-Elasmobranchii-Orectolobiformes-Hemiscylliidae-Chiloscyllium-G. griseum

Image: © Citron

Neonate blacktip shark (Carcharhinus limbatus)

This is the first neonate blacktip we caught for our research, and she was also our smallest shark. She measured under 60 centimeters for total length and only weighed about half a kilogram. Her umbilical scar was completely open, indicating that her birth occurred within the last two weeks.

After taking measurements and collecting blood and muscle tissue samples, she was released back into the sound.

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Megamouth Shark (Megachasma pelagios)

…a rare species of deep sea mackerel shark that has only been seen several times worldwide. Like the unrelated basking shark the megamouth is a harmless filter feeder using its modified finger-like gill rakers to capture food. Their mouths are also lined with luminous photophores which possibly help attract plankton. Despite their large (18ft) size megamouth sharks are poor swimmers and spend their nights in the depths, during the day they will arise to ‘shallower’ water to adjust for planktonic movement.

As of 2012 only 55 megamouth individuals are known and have been found all over the world, with most originating from the Pacific.  

Phylogeny

Animalia-Chordata-Chondrichthyes-Elasmobranchii-Lamniformes-Megachasmidae-Megachasma-M.pelagios

Images: Unknown and OpenCage

Broadnose sevengill shark - Notorynchus cepedianus

N. cepedianus is a member of the Notorynchus genus (part of the cow shark-family), and is easily recognizable by the seven gill slits it has (while most sharks only have five) and the lack of a first dorsal fin. Mature sharks can reach lengths of 1,7 meters, and live in the Pacific Ocean in shallow parts around beaches. 

Pregnant sharks move to shallow waters to give birth to as much as 82 pups. Like a lot of other sharks, N. cepedianus is ovoviviparous and “lays eggs” inside the womb.

Animalia - Chordata - Chondrichthyes - Elasmobranchii - Hexanchiformes - Hexanchidae - Notorhynchus - N. cepedianus

Photo-credits:
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References:
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Hatching Shorttail fanskate (Sympterygia brevicaudata) The capsule from where it left is an egg case or egg capsule, colloquially known as a mermaid’s purse or devil’s purse, is a casing that surrounds the fertilized eggs of some sharks, skates, and chimaeras. Has small openings (respiratory slits) where it enters and leaves the water, so the embryo can breathe…

  • video: Mylene Seguel
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Reef Manta Ray (Manta alfredi)

…a large species of Eagle Ray (Mobulidae) which is widely distributed throughout the tropical and subtropical Indo-Pacific, although a few individuals have been reported in the tropical East Atlantic. Like its more popular cousin (M. birostris) the reef manta ray is a gentle drifter, travelling along coastal habitats whilst filtering the water around it for nutrients. 

Classification

Animalia-Chordata-Chondrichtyes-Elasmobranchii-Myliobatiformes-Myliobatidae-Manta-M. alfredi

Images: Shiyam ElkCloner and Bartek.cieslak